Plate fin insert



July 15, 1958 F. H. RI NN PLATE FIN INSERT Filed Aug. 8, 1956 INVENTOR FREDERICK H. RINN United States Patent 2,843,787 PLATE FIN INSERT Frederick H. Kim, Flemington, Pa., assignor to Sylvania Electric Products Inc., a corporation of Massachusetts Application August 8, 1956, Serial No. 6tl2,852 1 Claim. (Cl. 313--356) This invention relates to beam power tubes and in particular to the structural form of the anode to adapt it for better association with other electrodes within the tube to attain better operation of the tube.

This type of tube, like a pentode, has a family of platevoltage vs. plate-current curves, with different control grid voltages, characterized by a sharp rise in plate current with initial increase in plate voltage and a subsequent fairly flat portion with increasing plate voltages. At the juncture of the two portions of the curve, a sharp bend or knee occurs. When this knee is at high plate potential levels, this tube gives rise to R. F. radiations. On a television set such R. F. radiations may be picked up by the antenna or parts adjacent the tube, and transmitted through the set, giving rise to jagged vertical lines at the right hand side of the picture tube, those lines being known in the art as snivets. At lower plate potential levels of the knee such conditions do not arise.

It is an object of this invention to prevent the occurrence of these snivets by creating a beam power tube with a lower knee characteristic.

In the prior art lowering of the knee voltage had been accomplished by bringing portions of the tube anode closer to the grids but with the portions of the anode sufiiciently spaced from the beam confining plates as to prevent flash over. Thus protuberances had been extruded from the anode toward the grids, or fins had been welded between anode halves to extend the anode electrostatically closer to the grids. It is to an improvement on the latter type of construction that this invention is directed.

In the prior art these fins were made of strip material jig-held to one half of the anode and welded while so held. This necessitated a special jig for each type of tube made and a welding operation for fastening the fins to the half anodes apart from any welding of the two halves of the anode to each other.

It is an object of this invention to provide a fin insert construction of such character as to lend to ease of fabrication of the anode portion of a beam type tube, without the use of jigs and with a reduction in the number of welding operations required.

How this object is accomplished as well as how other advantages are obtained will be made clear on reading the following specification when taken in conjunction with the accompanying drawing in which Fig. 1 is an elevational view of a tube mount with one half of the anode removed.

Fig. 2 is a perspective view of the novel assembly of anode halves and knee voltage reducing inserts.

Fig. 3 is an exploded view of the assembly, showing a modified form of anode half.

Referring to the drawings with greater particularity, in Fig. 1 there is illustrated a portion of a beam power type mount, in which there is shown a pair of insulating spacers 10, 12 as of mica, between which is held in properly spaced relation a cathode 14 with its filament leads 16, a pair of grids in aligned relationship so that only the No. 2 or outer grid 18 with its grid side rod 20 is visible, a small part of the beam confining plate 22, and one half 24 of the anode 24, 25. Fitted onto the half anode 24 are the metal inserts 26.

The half 24 of the anode is a U-shaped channel bar with wide flanges 28, each with tabs 30, as is conventional in the art, to pass through and lock over the spacers, and with struck out tongues 32 for interlocking with the other half 25 of the anode. The half anode 24 is also provided with edges 34 bent or curved out of the plane of the flange to nest with reversely bent or curved edges 36 on complementary anode half 25. The anode half 25 has flanges 29 with apertures 38 .registering with the tabs 32 when the anode halves are held together with the inserts sandwiched in between. The half anode 25 may or may not be provided with tabs at the upper and lower edges such as the tabs 30.

There are two inserts 26 for each tube and they may be identical with one another so that one stamping equipment will produce both inserts. When incorporated with the anode assembly, one is rotated with respect to the other, about a horizontal axis. Therefore, only one kind of insert for a given type of tube is necessary. The insert 26 is generally trapezoidal in shape with the longer edge 40 bent to nest in snugly with the bent edges 34, 36 of the anode halves. It is also provided with apertures 42 to register with the apertures 38 in anode half 25. The insert is made wide enough to penetrate the plane of the beam confining plate 22 of which the tie bars of the upper and lower edges of the windows are shown in section in Fig. 1, and extends toward the No. 2 grid. The upper and lower edges 44 of the inserts are bevelled or lowered to prevent the inserts from contacting the edges of the tie bars of the beam confining plate and to be spaced away sufficiently from the plate to prevent are or flash over. The leading edge 46 of the insert may be serrated or straight depending on design function of the insert.

In assembling parts, it is merely necessary to slip the insert over the tongues 32 of the anode half 24 and then slip the other half 25 of the anode over the same tongues. Bending of the tongues or bending of the tongues and spot welding at the edge portions of the flange portions 28, 29 and the interleaved inserts 26 holds the anode assembly together. Since all of the tongues 32 are on one anode half and the inserts are all uniform, assembly of parts is facilitated and since the inserts are wider than the width of the flanges or ribs 28, 29, heat radiation is enhanced. Further, better welding is attained because the inserts extend to the edge of the anode flanges at which the welds are easiest made.

Having thus described the invention, what is claimed is:

An anode and fin insert assembly comprising a pair of complementary anode halves, one half being provided with a flange portion terminating in a bent edge and having tongues struck out therefrom, and the other half anode having a flange portion with a bent edge complementary to the bent edge on the first half and also having apertures receiving the tongues and a fin insert lying between the flange portions and extending within the anode, said fin having a bent edge conforming with and nesting in between the bent edges of the two anode halves and having apertures through which the tongues pass, the

tongues being bent over the exposed face of the second half to form a tight assembly of half anodes and insert.

References Cited in the file of this patent UNITED STATES PATENTS 2,145,400 Loppacker Ian. 31, 1939 2,167,885 Glans Aug. 1, 1939 2,189,593 Putzer Feb. 6, 1940 2,615,138 Grimm Oct. 21, 1952 

